Posts Tagged 'velociraptor'

Although PLOS has many things to recommend it, one thing they don’t do is give you a lot of notice about publication and so actually the production of my recent paper on Protoceratops came shortly before the manuscript went online. As a result, although the paper had been around in various guises for several years, it was a bit too short notice to have everything ready for its publication, including both a press release from me and the following artwork.

The superb illustrator Andrey Atuchin had very generously got involved in producing an illustration to come out alongside the paper, but his recent illness coupled with the limited notice put everything back. However, I am delighted that he has now completed his new work and allowed me to put it up here.

Above is a simple (but fantastic) vignette of a single Protoceratops. This represents the age class of the block of four young animals that were the feature of the paper, with the reduced size of the frill and the overall proportions of the animal that does differ from what we see in adult animals. Although juvenile dinosaurs are often rare, there is a natural tendency for only full adults to be illustrated, or we see young animals only in the context of their parents or part of a herd and it’s great to be able to focus on a single animal, especially when the adult is already so familiar.

This then makes the whole composition below rather unusual and of course very fitting for the paper. We see the group of juveniles together, devoid of adult supervision or as part of a herd but in their apparently natural aggregation. The environment of course reflects the Mongolian Late Cretaceous with a very sandy region and little real plant life. The overall composition though hints at the wider issues of the paper in a nicely understated way – the group are largely at rest, though remain vigilant and the fact that there are multiple individuals means even those not directly scanning the environment are not that vulnerable and the group as a whole are looking in multiple directions. Staying vigilant is especially important for young and vulnerable dinosaurs lacking the size, experience and defences of adults, and so they must with here a pair of Velociraptor on the horizon.

My thanks of course to Andrey (who retains the copyright on these, please don’t share without permission) for this wonderful rendition of group living in the Cretaceous and nice of him to sneak some theropods in there so I can forget about my fall from grace and pretend that this is not just about ornithischians. It’s a wonderful piece and it really does convey not just the contents of the paper, but the issues at the heart of it, and even if you disagree with the hypotheses, it’s certainly evocative and really does show the concepts magnificently.

Yesterday I covered the basic introduction to my new paper about a Velociraptor specimen with an azhdarchid element preserved in it’s gut. Today I want to move on from the basics (what is there) to what this potentially means and how this is inferred. Most of my recent research is based around theropod ecology and behaviour (like this, this and this for example) and specimens like this one can provide new information and evidence for how these animals were acting. The obvious question here is why is this inferred as scavenging and not predation? As usual with such questions going so far back in time, it’s hard to be definitive, but this is the better supported inference.

First off there is the relative sizes of the animals. While it’s not unknown for predators to tackle other predatory animals, or relatively big prey it’s certainly not normal. Lions don’t routinely hunt leopards or bears go after wolves. This is relevant here since azhdarchids were most likely active predators themselves and so a potentially dangerous animal to attempt to kill. Moreover, the azhdarchid in question was most likely 9 kg in weight with a 3 m wingspan (and could have been considerably larger), while the Velociraptor was a sub-adult of around 13 kg. In short if this was a predation it was no mean feat – perhaps the equivalent of a small coyote bringing down a big eagle. Sure it’s possible, but it’s not unreasonable to think this was really very unlikely. It’s more likely this was a young carnivore scavenging on the carcass of a dead pterosaur, as indeed was inferred for a similar previous specimen from Canada.

Even if we assume that it was a kill, other things don’t add up well to support this. Theropods don’t tend to consume large amounts of bone like this. They might consume relatively large items (like a whole small prey item) but not large chunks of bone like this. And it is a pretty big chunk of bone, probably the same length as the skull of the dromaeosaur. Moreover, we also know that theropods can be really quite delicate feeders, including other velociraptorines. The tendency seems to be to scrape meat free of the bones, now chew up and swallow whole ones (like modern birds of prey, they’ll swallow a mouse, but will pull chunks off of rabbit or sheep). Carcass consumption patterns by modern vertebrates also show that whole big bones like that don’t tend to be swallowed. Finally, the pterosaur weighted at least half and potentially more than the dromaeosaur. Given their apparent skill at stripping a carcass of meat I don’t think I dromaeosaur would be swallowing whole bones (and ones that would be pneumatic, not filled with marrow) when much of it’s own weight was sitting there in muscle and viscera.

In short, predators don’t normally predate other predators. Predators (including theropods) don’t usually seek out large prey. Predators (including theropods) don’t usually consume large bones of large prey unless they are a bone specialist or there’s nothing left. Even when there’s not much meat left, theropods tend to scape this free to eat rather than swallow bones. Sure all of these could hit the ‘least likely’ option and it’s a who-knows-what to 1 chance that a small dromaeosaur took on a big azhdarchoid, killed it and started swallowing big bones. But it’s far more reasonable to infer that it scavenged the last bit of a carcass it chanced across.

We are then left with scavenging as the most likely explanation as to why this animal was swallowing whole bones. Interestingly, we do also see shed teeth being a common feature of dromaeosaur (and indeed theropod in general) feeding yet here every tooth in the skull is intact. That is admittedly merely a soupscon of evidence for scavenging, but one might well expect a tooth or two to be lost during a fight with such a big adversary. or even biting through bones to swallow them again suggesting it just picked up and swallowed what it could find without much or any oral processing.

Uncoloured version of Velociraptor feeding. Courtesy of, and copyright to Brett Booth.

Moving on from this issue then, what does this tell us about the ecology of dromaeosaurs? Well to degree, not much we didn’t know already. There’s already evidence for both predation and scavenging in the dromaeosaurs, and indeed already evidence they were eating pterosaurs. Even so, more evidence is always good, and it does at least reinforce the existing evidence we have. It also therefore takes us a little further away (sadly) from the idea that dromaeosaurs were some kind of hyper-carnivorous super-predator that spent their time knocking down huge prey items with all their claws and teeth. I say sadly, because it’s a great idea and a wonderfully romantic notion, but sadly these animals were every bit as opportunistic as other carnivores and clearly were not beyond taking the odd, or indeed regular, free meal through scavenging. Indeed given the number of specimens we now have supporting a scavenging interpretation, this does seem to have been a pretty common part of their behavioural repertoire as carnivores.

So yesterday at short notice I rushed up this teaser post which seemed to do the trick, and now I’ve got a bit more time on my hands, I can start putting down a proper post on the subject. Yep, I have a new paper out and this time featuring dromaeosaurs and pterosaurs. Long time readers will remember that almost exactly 2 years ago I had another paper out on dromaeosaur scavenging featuring shed teeth and bite marks on some Protoceratops material. Coupled with the famous fighting dinosaurs specimen we have pretty good evidence for dromaeosaurs, and specifically Velociraptor for feeding on this dinosaur. The record of dromaeosaur predation and feeding is actually pretty good compared to other theropods groups and there is also an isolated pterosaur wing bone from Canada with shed dromaeosaur teeth and bite marks.

This ‘new’ specimen marks the first record of gut contents for Velociraptor and the first record of a pterosaur bone as gut content in a theropod. (The ‘new’ is becuase this specimen was actually found in the 1990s, but has yet to be described, though I’m told there’s a photo of it in Luis Chiappe’s recent birds book). Thus we do have rather exceptional evidence for a Velociraptor chowing down on an azhdarchid.

And here it is, well part of it. The Velociraptor in question was remarkably well preserved and complete which allowed the preparation of it with the chest cavity as a single articulated piece with the vertebrae, sternum, ribs, gastralia and even uncinate processes all intact and in their original positions. The bones are really well preserved and much of the material has been prepared free of the matrix entirely. One obviously example is the skull which, bizarrely, is on display in Barcelona so at least some reader might have already seen that, though sadly I haven’t and had to rely on some superb photos kindly sent by Fabio Dalla Vecchia. It’s hard to show the bone off properly what with the whole ribcage in the way (which is, incidentally, a broken ribcage, one of the ribs took a huge battering and shows a healed break – white arrow in the above picture). S you’ll be delighted to know there are also some close-ups in the paper like this one (below) and even some CT scans in the supplementary data.

Close up of the bone. From Hone et al., 2012

As you can see the bone is incredibly thin-walled which is the major reason that it’s inferred to be an azhdarcid pterosaur, though their presence in the Late Cretaceous, including a related formation, and the general absence of other pterosaurs in the Late Cretaceous helps support this identity. Given what is around and the thinness of the bones, it’s pretty unambiguous as indeed is the identification of the dromaeosaur as Velociraptor given that we have basically the whole thing. In short, this is about as convincing a case as one could make that a Velociraptor had eaten an azhdarhid. But was it really scavenging? Well that and other issues I’ll be talking about tomorrow, as there’s quite a lot more to say on this. Stay tuned.

Well at least of what it is should be pretty obvious based on the picture (which comes courtesy of and copyright to Brett Booth, of Carnosauria fame). I’ll be explaining all more fully as soon as I get the time, but after having been sitting on this for quite some time and then suddenly getting the opportunity it seemed a shame not to put up this beautiful picture right away. More to come very soon, promise.

Feet seem to have become the order of the day of late as one idea has spread through and I realise there’s more to say on them. On that note, on to perhaps the most famous of feet in the dinosaur world, that of the dromaeosaurs. Yes it’s time to look at the killer claws on Deinonychus (pictured). Actually, it’s a pretty terrible photo that doesn’t show off all of what I want to to talk about but it’s all I got right now (though you can get some more bits here and here).

You can see that the hallux is present and again quite large, which means that the famous ‘raptorial’ claw is therefore on the end of digit 2. This is indeed bigger than those of digits 3 and 4 which help to make it stand out, but it’s the position that it’s capable oh holding that makes it truly interesting. While the claw itself is somewhat specialised, the ‘cocked’ position of the claw is ultimately more down to the specialised phalanx it sits on. That has a rather unusual shape and to a degree, the end connecting with the claw looks almost upside-down.

The joints of finger and toe bones in theropods generally have a little roller joint between the bones (the joint between the phalanx and claw on Linhenkyus shows this really well). But in the specialised one here, that roll can carry on right over the back of the bone to pull the claw right back, and that last phalanx can pull almost the same trick too. That’s what gets the claw cocked in the incredible position (and if you’ve tried bending your fingers back at the joints you’ll know that’s otherwise quite tricky).

This does incidentally appear to be the normal ‘resting’ posture for the toe as shown by footprints of theropods with just two toes showing and a bulge from the base of digit 2. These are dromaeosaur tracks. Well, probably, since actually troodontids pull the same trick so telling one set of tracks from the other is tricky (though people are working on this) but the general point should still hold true of the toe being held in this position while walking around.

Most people who have read even a little on dinosaurs at some point will have seen a photo, cast, model or reconstruction of the famous fighting dinosaurs (and if not, then follow the link to see them). However, while this fascinating fossil certainly tells us that at least one Velociraptor took on a Protoceratops this is pretty much the limit of our knowledge of their interaction from the fossil record. Protoceratops is by far the most common herbivore in the fossil record in which it is found (and of course close relativels like Magnirostris) and Velociraptor (or perhaps rather these days velociraptorines thank to thinks like Tsaagan and Linheraptor turning up) the most common predator. Although the two are quite similar in size, the abundance of both and the abundance of fossils would suggest that the two would have some sort of trophic relationship. i.e. the carnivore would be eating the herbivore in some way at some point.

Naturally one would expect a small predator like Velociraptor to target small prey (like juvenile Protoceratops perhaps) but that hardly rules out their taking the odd swipe at elderly or ill individuals or of scavenging from carcasses. If that was the case, then were is the evidence? Tantalisingly the famous CCDP (Chinese-Canadian Dinosaur Project) team reported often finding velociraptorine teeth with the bones of ornithischian dinosaurs, but without saying which ones they were, so while Protoceratops is the most obvious candidate we can’t say for sure. However, my new paper (you saw this coming, right?) describes a better association – velociraptorine teeth in association with a Protoceratops skeleton and feeding traces to boot.

I’m quite pleased with this work if only because it’s the first paper based on something I found and then wrote up which is rather nice. Credit must go to coauthors Jonah Choiniere and Mike Pittman who originally found the teeth and brought them back to camp. I had the bit of info on the CCDP report in my head and had been thinking about bite marks at the time, so after some pestering they took me to the site and together with Corwin Sullivan we started to sort through all the bone fragments to look for any with bite marks on them. Despite the intensive weathering of the bones, there were some pieces with drag marks from small teeth so we collected what we could and took it back to Beijing.

This paper reports on these finds and as noted above it consists of a couple of dromaeosaur teeth found in association with various bones with some of those bones bearing trace marks. I won’t labour the details, since it’s all in the paper, but I would like to talk about the implications here – are the fighting dinosaurs a one off, or did Velociraptor regularly go after Protoceratops.

As noted above the two animals are similar in length though of course in terms of build and body mass, the Protoceratops would have been the far bigger animal. That suggests that the dromaeosaurs would be unlikely to want to tackle something that big. Those who immediately want to leap and cite the fighting dinosaurs will hit two problems, first and most obviously, this is a single record of a single incident and it’s hard to say if it’s unique or not. Perhaps the Proto was already ill or injured, or the dromaeosaur was desperate, or who knows what. Secondly, big though the Protoceratops is in the fighting dinos pair, it’s actually probably not an adult and is only about 2/3rd adult size, so may have been a more tempting target for a predator (if obviously not a small juvenile).

Protoceratops teeth recovered at the site of our new record are pretty big and there were some fragments of big bones and over a big area suggesting these were the remains of a hefty animal. This would have been quite a challenge for a dromaeosaur to try and bring down. Even if it had, how much could it eat? The bite marks we found were on areas of bone associated with the jaws, hardly the most flesh-rich of areas, and there were multiple repeated bites. Why was this happening?

Velociraptor gets scavenging. Image courtesy of Brett Booth.

The conclusion we offer is that this is the result of scavenging. It’s unlikely a dromaeosaur could bring down such a big Protoceratops. Even if it did, there’d be tons of meat available on the legs and belly and the tail – there’s no need to go and scrape off what little lies on the jaws. Hell, even a whole group would probably get enough food from an animal that big without having to start chewing on the scraps on the face to the degree that they leave so many small marks on the bones. In short, this really looks like a dromaeosaur came across a corpse and scraped off it what it could (a meal is a meal) losing a couple of teeth and making some scrapes on the bones in the process. While this doesn’t support the idea of dromaeosaurs tacking big protoceratopsians for food, it does provide evidence that the former were probably feeding on the latter, even if that largely consisted of scavenging. Still, while such a relationship might be expected, it’s always good to find new information to support ideas and further understanding of the problems.

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Astute readers will have noted that the paper is not actually out yet. However, the journal in question released the proofs version early and the media have picked up on it. I did check with the journal and as far as they are concerned there’s no embargo on it. Since the press have already picked up on it, it would be silly for me not to mention my own research. However, please don’t ask me for a copy of the paper, I don’t have the final version yet and there are things being added to the proofs. My hand is therefore rather forced by others.

Finally a huge thank you to Brett Booth of the Carnosauria blog for producing the images above at short notice and in colour too. The artwork is Brett’s and should not be used without his permission.

One of the most exciting things that our excavations uncovered at Bayan Mandahu in the last two years can finally be revealed. Alvarezsaur expert Jonah Choiniere gets the credit for spotting a curved claw poking out of the sand back in 2008 while out prospecting with Mike Pittman. A quick dig revealed there was quite a bit more bone present of some theropod or other. However, as with many such events, the specimen was dug out and put in a plaster jacket without uncovering it so that it was protected from damage. Therefore it was only months later back at the lab when the jacket was opened and preparation of the specimen done that it was clear what was inside. It was this:Continue reading ‘Linheraptor – another new dromaeosaur’

So having covered ornithischian ossified tendons it’s time to switch to the other side of the dinosaurian tree and take a look at the hyper elongate zygopophyses of dromaeosaurs. This is a bizarre feature of dromaeosaur tails where the (normally) little articulation points between vertebrate (the pre and postzygopophyses) are elongated such that they overlap other individual vertebrae rather than just articulating with each other. The postsygos (at the rear) are only mildly elongate compared to the truly mammoth prezygos which can overlap half a dozen or more bones.

Here, several have become disarticulated so that the individual shafts of the zygopophyses stick out free of the tail making them more visible. Just about visible (it’s not the greatest image) is the fact that these are part of the vertebrae and continuous with them and are not separate elements as are the ossified tendons of the ornithischians. A good look under a microscope makes that pretty clear, though of course a bad photo shot through glass in a museum doesn’t always. Also worth noting is the fact that under the tail, the chevron bones are also massively elongated too.

It’s tempting to assume that this makes the tail an incredibly stiff rod-like structure and this has been suggested in the past, but this is not likely to be the case. For a start this specimen is hardly unique in that the bones have separated out from each other even when the rest of the skeleton remains articulated, so clearly if even a fairly mild disturbance after death can move the bones around, then in life there must have been a degree of flexibility. Secondly, other specimens are preserved with the tail flexed to a degree suggesting that things are not that rigid. Finally, it’s pretty unlikely that the whole thing was exceptionally rigid as this would make it prone to breaking – even our own long bones can flex at least a bit when stressed without snapping, and some long and thin bones (like this one for example) pretty much must have had some flexibility or they’d break constantly – bones are not always very rigid (and indeed as an aside, bat bones are incredibly flexible). So while the tail was undoubtably stiffened, it was unlikely the flag-pole that some people think it was.

There are many dinosaur (and other fossil) specimens that are famous not so much for what they are as what they show (as with Big Mama featured here the other day). A complete T.rex is all very well (and very useful and interesting and fundamentally cool, I’m happy to admit), but some things are so incredibly rare and unlikely to preserve that to have them as fossils is truly amazing. The most obvious archosaurian example of this is the famous fighting dinosaurs of Mongolia that show a Velociraptor and Protoceratops locked in combat. These have become the subject of much analysis and much speculation as to quite how they died and got preserved in such a posture.

I’m going to join in that debate any further but merely point out that the Velociraptor has its foot claw jammed up in the throat region of the Protoceratops, but equally has its arm stuck in the mouth of its adversary. They may or may not have died together, but it is certainly possible that this was a case where each killed the other. It’s also worth noting that they are preserved pretty much in 3-D and have not collapsed into the sand as one might expect, something that is actually quite common in specimens from the area.

These photos are of a fantastically well made cast of the pair that are on display in Japan. While photos of the original have been reproduced many times in all kinds of media, they always seem to be of the same shot, or at least one taken from the same angle, so hopefully these will provide some interest.

While the photos are mine, I have graciously been given permission to post these by the Fukui Prefectual Museum. Please do not reproduce these.